class AppDelegate
  def application(application, didFinishLaunchingWithOptions:launchOptions)
     @window = UIWindow.alloc.initWithFrame(UIScreen.mainScreen.bounds).tap do |win|
        win.rootViewController = AsyncController.alloc.init
        win.makeKeyAndVisible
     end
     true
  end
end

class AsyncController < UIViewController
   def thread1
     10.times { |i| NSLog("\t Thread1: %@", i) }
   end

   def thread2
     20.times { |i| NSLog("\t\t  Thread2: %@", i) }
   end

   def thread3
     30.times { |i| NSLog("\t\t\t   Thread3: %@", i) }
   end
   
   def viewDidLoad
      self.view.backgroundColor = UIColor.whiteColor
      @queue = NSOperationQueue.new
      @queue.maxConcurrentOperationCount = 3 
      @queue.name = "threads operation"
      
      operation1 = NSInvocationOperation.alloc.initWithTarget(self, selector: :thread1, object:nil)
      operation2 = NSInvocationOperation.alloc.initWithTarget(self, selector: :thread2, object:nil)
      operation3 = NSInvocationOperation.alloc.initWithTarget(self, selector: :thread3, object:nil)
      
      @queue.addOperation(operation1)
      @queue.addOperation(operation2)
      @queue.addOperation(operation3)
   end
end